Recent studies have demonstrated the potential of natural plant essential oils (EOs) as alternatives to chemical preservatives due to their notable antimicrobial activity, rapid biodegradability, and high safety profile. The aim of this study was to evaluate the chemical composition and biological activities of essential oil from Melaleuca alternifolia (tea tree). GC-MS analysis identified 31 volatile compounds, with γ-terpinene (25.3%) as the dominant component. Antioxidant activity was assessed using DPPH and ABTS assays, yielding IC₅₀ values of 28.07 mg/mL and 0.51 mg/mL, respectively. Antimicrobial efficacy was tested against twelve microorganisms using the disc diffusion method and determination of minimum inhibitory concentrations (MIC). The largest inhibition zones were observed against biofilm-forming Salmonella enterica (11.33 mm) and S. enterica (10.33 mm), with MIC50 values ranging from 0.16 to 8.08 mg/mL. The highest in situ inhibition was recorded on the kiwi model against Yersinia enterocolitica (88.83%), on pear against Staphylococcus aureus, on parsley against Listeria monocytogenes, and on radish against biofilm-forming S. enterica all at the highest applied concentration of 500 µL/L. Anti-biofilm activity was evaluated using crystal violet staining and MALDI-TOF MS Biotyper spectral profiling. Spectral differences in MALDI-TOF MS profiles between planktonic and biofilm cells suggest that tea tree essential oil triggers distinct bacterial responses depending on physiological state and surface material. Insecticidal activity against adult Megabruchidius dorsalis yielded LC50 and LC90 values of 20.60% and 54.46%, respectively, with 100% mortality recorded at 100% essential oil concentration. These findings highlight the broad-spectrum bioactive potential of tea tree essential oil and its promise as a natural biocidal agent.
Raw-material assessment usually treats wood quantity and density separately and takes whole-tree density from a single breast-height disc. We quantified whole-stem wood basic density and its associations with radial growth and competition under two contrasting management scenarios of Larix olgensis A. Henry in northeast China, and translated the tree-level relationship into stand-level oven-dry biomass supply. Density was measured on 666 segments from 51 of 54 felled trees, giving whole-stem series for 49. In mixed models with trees nested in plots, density declined from base to crown (−0.101 g cm−3 per unit relative height) and increased with cambial age (+0.0043 g cm−3 yr−1), and stems in the mature stand were denser throughout. A negative growth–density association was detected within the mature but not the young/dense stand, and mediation analysis did not support a competition → growth → density pathway. Despite 2.7 times more stems, the young/dense stand supplied an estimated 56 against 217 m3 ha−1 of volume and 24 against 109 t ha−1 of oven-dry stem biomass, with 11 against 53% of it in the densest band. Its share of the mature supply was 26% by volume but 22% by mass, so volume alone overstated it by 19% (95% CI 13–26%). A single breast-height disc overestimated whole-stem density by 0.035 g cm−3, inflating estimated stand biomass by 6–11%. Because each scenario is a single, purposively sampled stand confounding developmental stage, stand density, thinning history and site, these associations are restricted to the stands sampled.
Nitrogen availability is a major factor limiting the growth and productivity of the medicinal plant Panax notoginseng. Members of the nitrate transporter 1/peptide transporter family (NPF) play a critical role in nitrate uptake, transport, and signaling. However, their functions in P. notoginseng remain largely unknown. In this study, 70 NPF genes were identified from the P. notoginseng genome and classified into 8 subfamilies based on phylogenetic relationships. Gene structure, conserved motif, chromosomal distribution, and collinearity analyses indicated that the PnNPF family is evolutionarily conserved. Low nitrogen supply promoted root system development and enhanced the activities of several nitrogen metabolism enzymes. Transcriptome profiling revealed that a large proportion of PnNPFs are induced under low-nitrogen conditions. WGCNA and PPI analyses identified PnNPF4.13 as a candidate hub gene associated with root architectural traits. Structural modeling and molecular docking suggested a potential role of PnNPF4.13 in nitrate transport.Subcellular localization confirmed that PnNPF4.13 is localized to the plasma membrane.Heterologous expression of PnNPF4.13 in Arabidopsis significantly increased root growth under various nitrogen supply conditions.These findings provide a comprehensive overview of the NPF gene family in P. notoginseng, and identify PnNPF4.13 as a nitrogen-responsive candidate gene associated in root architectural adaptation to nitrogen availability.
Fritillaria unibracteata, an endangered medicinal plant endemic to the Qinghai–Tibet Plateau, produces seeds characterized by prolonged dormancy and low germination rates, thereby severely limiting artificial propagation, germplasm conservation, and sustainable cultivation. This study optimized a two-stage low-temperature stratification treatment and integrated physiological, transcriptomic (RNA-seq), and non-targeted metabolomic (LC–MS) analyses to investigate the physiological and molecular changes during seed dormancy release. Seeds began to germinate after 180 days of stratification, reaching a germination rate of 92.63%, indicating that prolonged low-temperature stratification effectively promoted seed dormancy release under the experimental conditions used in this study. During stratification, gibberellic acid (GA₃) content increased, whereas abscisic acid (ABA) content and the ABA/GA₃ ratio decreased. Starch, soluble protein, and soluble sugar contents declined markedly. Key enzyme activities involved in glycolysis, the tricarboxylic acid (TCA) cycle, and the pentose phosphate pathway increased, whereas catalase (CAT) and peroxidase (POD) activities decreased. Transcriptome analysis and WGCNA revealed significant enrichment of pathways related to lipid storage, energy metabolism, and hormone signaling. The diterpenoid biosynthesis pathway and GA signaling were consistently enriched across stratification stages. WGCNA identified GA2ox as a hub gene, while multi-omics integration revealed significant correlations between flavonoid biosynthesis genes and metabolite accumulation. CCoAOMT expression was positively correlated with the accumulation of multiple flavonoids, including quercetin, epicatechin, and xanthohumol. Collectively, the results indicate that seed dormancy release during cold stratification is associated with coordinated changes in hormone balance, reserve mobilization, energy metabolism, and flavonoid metabolism. These findings provide an effective strategy for seed treatment and cultivation, thereby facilitating the large-scale propagation, sustainable cultivation, and industrial utilization of F. unibracteata.
Salt stress is a critical abiotic factor limiting tree and crop growth. Multi-walled carbon nanotubes (MWCNTs) exhibit potential in improving plant salt tolerance, their practical application is hindered by poor aqueous dispersion. In this study, carboxylated MWCNTs (c-MWCNTs) were prepared and compared with pristine MWCNTs (p-MWCNTs) in poplar seedlings exposed to 200 mM NaCl. Carboxylation improved the dispersion of MWCNTs and enhanced their surface association with Na+. However, direct adsorption accounted for less than 1% of the total Na+, suggesting that Na+ removal induced by c-MWCNTs was not the main factor contributing to the seedling salt tolerance. Under salt stress, c-MWCNTs maintained root cellular structure, increased H+-ATPase activity, and promoted a more negative membrane potential. They also enhanced K+ and Ca2+ fluxes, mitigated root Na+ accumulation, and increased Na+ content in leaves, thereby shifting the Na+ distribution between roots and shoots. Moreover, c-MWCNTs treatment enhanced the activities of antioxidant enzymes, elevated soluble sugar concentrations, and improved the maximum quantum of PSII (Fv/Fm) in leaves. Overall, c-MWCNTs improve salt tolerance in poplar through root interfacial regulation, ion homeostasis, and physiological adjustment. These findings show that surface functionalization can shape root nanomaterial interactions and support the use of carbon nanomaterials in salt affected environments.
